Car Technology called 'Stop-Start System' Will Come to U.S.

August 9, 2012

Published: August 9, 2012

DETROIT — The stop-start system, a technology that shuts off a vehicle's engine when stopped in traffic, is now making its way to the U.S. from overseas where such systems are already in common use. Other names for this technology include idle elimination, idle-stop-go, and micro-hybrid.

Lux Research predicts that more than 8 million vehicles in North America will be equipped with engine stop-start systems by 2017. What does this mean for American motorists? AAA experts examine the technology.

Early versions of stop-start technology date back to the 1980's, and today over 40 percent of the new cars sold in Europe and Japan use this gas saving technology.

"Engine stop-start isn't a brand new technology, but the latest systems benefit from significant advances made in the last few years," said John Nielsen, AAA's director of automotive engineering and repair. "This technology is only going to gain momentum as vehicle manufactures work to meet the more stringent Corporate Average Fuel Economy standards set for 2016."

The information below on engine stop-start systems comes from the recently formed AAA Automotive Engineering team, which is based at the association's national office in Heathrow, Florida:

What is stop-start? Stop-start technology automatically shuts off the engine when a driver is stuck in traffic or waiting for a red light to change. By doing so, the system can improve fuel economy up to 12 percent and contribute to a reduction in vehicle exhaust emissions.

How does it work? With an automatic transmission, engine shutdown occurs when the vehicle is stopped for several seconds with the brake pedal applied. With a manual transmission, shutdown takes place with the transmission in neutral and the clutch released. As soon as the brake pedal is released, or the clutch pedal is depressed, the engine restarts automatically.

How much does it cost? On some models, the stop-start system is standard equipment and its cost is included in the vehicle price. Where stop-start is offered as option it generally costs around $300.

How much can it save? If gasoline costs $3.75 per gallon, the owner of a car that normally gets 20 mpg and is driven 12,000 miles per year would save an estimated $167 per year in fuel costs if the vehicle were equipped with an engine stop-start system. In this case, the system would pay for itself in less than two years and offer ongoing savings thereafter.

Are there any downsides to stop-start? A major challenge in developing stop-start systems has been engineering the systems to meet consumer expectations. The engine stop-start transitions must be smooth and seamless, and drivers new to the technology will need to learn that engine shutdown at idle is a normal thing and not a sign of a problem. In some vehicles, heating and air conditioning performance could suffer if the engine remains shut down for an extended time. Finally, the larger and more powerful batteries that are required for stop-start systems will be more expensive to replace when the time comes.

What American market vehicles offer stop-start today? All hybrid cars have stop-start capability, although they use a different technology than the systems on conventional powertrains. The first non-hybrid stop-start systems in the U.S. market are on 2012 highline vehicles from BMW, Mercedes and Porsche. For the 2013 model year, Jaguar will join that select group, but stop-start systems will also become available on popularly priced models from Ford, Kia, and possibly others. Even trucks will start to see some systems with Dodge adding stop-start to its V6-powered Ram 1500 pickup for a one mile per gallon fuel economy improvement.